Currently, liquid crystal display devices are widely used in color televisions, personal computers, video display monitors, and mobile phones in view of low profile, light weight, and low power consumption. The types of display in such liquid crystal display devices include the direct view type and the projection type. In the direct view type, the image displayed on a liquid crystal display panel is directly viewed. In the projection type, the image displayed on a liquid crystal display panel is projected for display on a screen, car windshield and the like.
In the projection type liquid crystal display device, light stronger than that in the direct view type liquid crystal display device needs to be projected toward a liquid crystal display panel from its back surface in order to project an image. Thus, in order to prevent malfunctions due to light leakage of pixel driving switching transistors (TFT) placed in the display region, a light shielding layer is provided on the lower surface of the semiconductor layer of the TFT. If necessary, the front surface (upper surface) of the TFT is also light shielded against external light.
Furthermore, high definition pixels are needed to magnify the image displayed in a small display region of the liquid crystal display device. Thus, the liquid crystal display panel is often manufactured by the p-Si process. By adopting this p-Si process, a driving circuit for driving pixels such as a scanning line driving circuit can also be incorporated in the liquid crystal display panel by the same process. Thus, the configuration of a liquid crystal display device integrated with a driving circuit is in widespread use.
Patent Literature 1 (Japanese Unexamined Patent Application Publication 2009-69569) discloses a liquid crystal display device in which the aforementioned type of liquid crystal display device integrated with a driving circuit is provided with a light shielding film to shield light.